JP2006142470A - Robot overcurrent prevention device - Google Patents

Abstract

An overcurrent prevention device for a robot that protects an electrical system when a current is detected, and prevents a robot from stopping functioning or becoming unstable regardless of the situation. provide.
An FET 80a, which is inserted in a power supply circuit 7a and shuts off the power supply circuit 7a when the power supply circuit 7a is turned off, and a current sensor which generates an output corresponding to the current supplied to the electric motor. 80b compares the output V1 of the current sensor with the threshold value Va, and when the output of the current sensor exceeds the threshold value, executes a switching operation for turning on / off the switching element for a first predetermined time (T2). Overcurrent suppression means for intermittently shutting off the power supply circuit (comparator 80c, first and second delay circuits 80d and 80e, EX-OR circuit 80f, AND circuit 80g, oscillator 80h, buffer 80i, AND circuit 80j, insulation A gate driver 80k, a latch circuit 80l, and an ECU 70).
[Selection] Figure 6

Description

  The present invention relates to a robot, and more specifically to an overcurrent prevention device for a legged mobile robot.

Generally, in a robot, an electric system such as an electric motor is detected by detecting an electric current flowing through an electric motor that drives a joint, detecting an overcurrent compared with a threshold value, and suppressing the electric current when the overcurrent flows. Is protecting. As the prior art, one described in Patent Document 1 below is known. In the technique described in Patent Document 1, in the case of controlling the drive of a servo motor based on a given servo command, the threshold value is made variable according to the servo command, and the servo performance at high speed is improved. The current abnormality detection accuracy at low speed is improved.
JP 2001-022446 A

  In such a configuration, when energization is suppressed when an overcurrent is detected, the electrical system is protected, but depending on the situation, the robot function may stop or the posture may become unstable.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and when an overcurrent is detected, while protecting the electrical system, the robot stops functioning or its posture becomes unstable regardless of the situation. An object of the present invention is to provide a robot overcurrent prevention device which is to be avoided.

  In order to solve the above-described problem, in claim 1, a plurality of links connected through a joint, an electric motor disposed in the joint, a voltage source, the electric motor, and a voltage source In a robot provided with at least a drive circuit that is energized and driven by the electric motor in response to an energization command, the power circuit is inserted into the power circuit and turned off. The switching element to be cut off, the current sensor that generates an output corresponding to the current passed through the electric motor through the drive circuit, the output of the current sensor is compared with a threshold value, and the output of the current sensor is Overcurrent suppression means for intermittently shutting off the power supply circuit by executing a switching operation for turning on / off the switching element for a first predetermined time when the threshold value is exceeded. It was as configuration obtain.

  In the robot overcurrent prevention device according to claim 2, the overcurrent suppression unit may be configured to perform the first operation after a second predetermined time has elapsed when the output of the current sensor exceeds the threshold value. The switching operation is performed for a predetermined time.

  According to claim 3, the base, a plurality of legs connected to the base via a first joint, and a tip of each of the plurality of legs connected via a second joint And a plurality of electric motors arranged at each of the first and second joints, a voltage source, and a power supply circuit connecting the plurality of electric motors and the voltage source. And a switching element that cuts off the power supply circuit when turned off and inserted in the power supply circuit in a robot comprising at least a drive circuit that energizes and drives each of the plurality of electric motors according to A current sensor that generates an output corresponding to a current supplied to the plurality of electric motors via the drive circuit; and an output of the current sensor is compared with a threshold value. The threshold value for a predetermined period When more than it was composed as and a overcurrent suppressing means for cutting off the power supply circuit turns off the switching element.

  The robot overcurrent prevention device according to claim 4 further includes a temperature sensor for detecting an outside air temperature, and the overcurrent suppressing means sets the threshold based on the detected outside air temperature. Configured to change.

  The robot overcurrent prevention apparatus according to claim 5 further includes a temperature sensor for detecting an outside air temperature, and the overcurrent suppressing means is configured to perform the first predetermined operation based on the detected outside air temperature. It was configured to change the time.

  In the robot overcurrent prevention device according to a sixth aspect of the present invention, the overcurrent suppression means is configured to output an abnormal alarm signal when the switching element is turned off to shut off the power supply circuit.

  The robot overcurrent prevention apparatus according to claim 7 is configured such that the robot is a legged mobile robot.

  In claim 1, when the power circuit is inserted and turned off, a switching element that shuts off the power circuit, a current sensor that generates an output corresponding to a current that is passed to the electric motor via the drive circuit, The output of the current sensor is compared with a threshold value, and when the output of the current sensor exceeds the threshold value, the power supply circuit is intermittently cut off by executing a switching operation for turning on / off the switching element for a first predetermined time. Therefore, the power supply circuit is intermittently cut off only during the overcurrent flow to suppress the energization amount, thereby minimizing the decrease in the energization amount below the threshold value. In addition, while protecting an electrical system such as an electric motor, it is possible to avoid that the function of the robot stops or the posture thereof becomes unstable regardless of the situation.

  In the robot overcurrent prevention apparatus according to claim 2, the overcurrent suppressing means is configured to perform the first predetermined time after the second predetermined time has elapsed when the output of the current sensor exceeds the threshold value. Since the switching operation is performed, overcurrent can be reliably detected while eliminating the influence of noise and the like in addition to the above-described effects.

  According to a third aspect of the present invention, in a robot, more specifically, a legged mobile robot, a plurality of electric motors are connected via a switching element that is inserted into the power supply circuit and shuts off the power supply circuit when turned off. A current sensor that generates an output corresponding to the current supplied to the motor, and the output of the current sensor are compared with a threshold value. When the output of the current sensor exceeds the threshold value for a first predetermined period, the switching element is Since it is configured to include an overcurrent suppressing means that turns off and shuts off the power supply circuit, the power supply circuit is cut off only during the overcurrent flow, in other words, the emergency stop is performed to protect the electrical system such as the electric motor. Regardless of the situation, it can be avoided that the function of the robot stops or the posture of the robot becomes unstable.

  That is, in the case of a legged mobile robot, an overcurrent may temporarily flow through the electric motor due to the foot tripping on the road surface during movement (walking). Since the power supply circuit is cut off, that is, the emergency stop is performed only during the flow of the robot, the influence on the posture control of the robot can be minimized, so that the posture can be prevented from becoming unstable.

  In the robot overcurrent prevention device according to the fourth aspect of the present invention, the overcurrent suppressing means is configured to change the threshold value based on the detected outside air temperature. When the temperature is high, the threshold value can be optimally set according to the outside air temperature, for example, by lowering the threshold value so that overcurrent is easily detected.

  In the robot overcurrent prevention device according to claim 5, since the overcurrent suppressing means is configured to change the first predetermined time based on the detected outside air temperature, in addition to the effects described above, for example, When the temperature near the voltage source is high, the first predetermined time can be optimally set according to the outside air temperature, such as shortening the first predetermined time and stopping the energization at an early stage.

  In the robot overcurrent prevention device according to the sixth aspect of the present invention, the overcurrent suppression means is configured to output an abnormal alarm signal when the power supply circuit is shut off by turning off the switching element, that is, in an emergency stop. In addition to the effects described above, the user (operator) can recognize that an abnormality in which an overcurrent flows has occurred.

  In the robot overcurrent prevention device according to claim 7, since the robot is configured as a legged mobile robot, the function of the robot can be controlled regardless of the situation while protecting the electrical system such as the electric motor. Can be prevented from stopping or becoming unstable. That is, as described above, in a legged mobile robot, an overcurrent may temporarily flow in the electric motor due to a tripping of the foot portion to a protrusion on the road surface during movement (walking). Also in this case, since the influence on the posture control of the robot can be minimized, it is possible to avoid the posture becoming unstable.

  The best mode for carrying out a robot overcurrent prevention apparatus according to the present invention will be described below with reference to the accompanying drawings.

  Hereinafter, a robot overcurrent prevention apparatus according to a first embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a front view of a robot targeted by the overcurrent prevention apparatus according to the first embodiment, and FIG. 2 is a side view thereof. As a robot, a legged mobile robot, more specifically, a humanoid (human) legged mobile robot having two legs and two arms is taken as an example.

  As shown in FIG. 1, a robot (more specifically, a legged mobile robot) 1 includes a plurality of (two), more specifically two (book) legs 2, and above that, A substrate (upper body) 3 is provided. A head 4 is formed further above the base 3, and two (book) arms 5 are connected to both sides of the base 3. Further, as shown in FIG. 2, a storage portion 6 is provided on the back portion of the base 3. A battery (voltage source) 7 is stored inside the base 3, and an electronic control unit, which will be described later, is accommodated inside the storage unit 6. The robot 1 shown in FIGS. 1 and 2 is covered with a cover for protecting the internal structure.

  FIG. 3 is an explanatory diagram showing the robot 1 in a skeleton. The internal structure of the robot 1 will be described with reference to the figure. As shown in the figure, the robot 1 has six legs powered by eleven electric motors on the left and right legs 2 and arms 5, respectively. Provide joints.

  That is, the robot 1 has electric motors 10R and 10L (R on the right side and L on the left side) that drive joints that rotate the leg 2 about the vertical axis (Z axis or vertical axis) to the hip joint of the waist (crotch). And the electric motor 12 that drives the joint that swings the leg 2 in the pitch (advance) direction (around the Y axis), and the leg. An electric motor 14 that drives a joint that rotates 2 in the roll (left and right) direction (around the X axis) and a knee joint that rotates the lower part of the leg 2 in the pitch direction (around the Y axis) are driven at the knee. An electric motor 16 is provided, and an electric motor 18 that drives a foot (ankle) joint that rotates the tip side of the leg 2 in the ankle in the pitch direction (around the Y axis) and a foot that rotates in the roll direction (around the X axis) Electric ankle driving the joint Equipped with a 20.

  As described above, in FIG. 3, the joint is indicated by the rotation axis of the electric motor that drives the joint (or a transmission element such as a pulley that is connected to the electric motor and transmits its power). A foot (foot) 22 is attached to the tip of the leg 2.

  As described above, the electric motors 10, 12, and 14 are arranged at the hip joints of the leg 2 so that the rotation axes thereof are orthogonal to each other, and the electric motors 18 and 20 are rotated at the ankle joint (ankle joint). It arrange | positions so that an axis line may orthogonally cross. The hip joint and knee joint are connected by a thigh link 24, and the knee joint and ankle joint are connected by a crus link 26.

  The leg 2 is connected to the base 3 via a hip joint, but the base 3 is simply shown as a base link 28 in FIG. As described above, the arm portion 5 is connected to the base 3.

  The arm part 5 is also configured similarly to the leg part 2. That is, the robot 1 includes an electric motor 30 that drives a joint that rotates the arm portion 5 in the pitch direction and an electric motor 32 that drives a joint that rotates the roll portion in the roll direction at the shoulder joint of the shoulder portion. An electric motor 34 for driving a joint for rotating the arm and an electric motor 36 for driving a joint for rotating the subsequent portion on the elbow, and an electric motor 38 for driving a wrist joint for rotating the joint on the tip side. Prepare. A hand (end effector) 40 is attached to the tip of the wrist.

  That is, the electric motors 30, 32, and 34 are arranged at the shoulder joints of the arm portion 5 so that their rotation axes are orthogonal to each other. The shoulder joint and the elbow joint are connected by an upper arm link 42, and the elbow joint and the wrist joint are connected by a lower arm link 44.

  Although illustration is omitted, the hand 40 includes a driving mechanism for five fingers (finger) 40a, and is configured to be able to perform operations such as gripping an object with the finger 40a.

  The head 4 is connected to the base body 3 via an electric motor (which constitutes a neck joint) 46 around a vertical axis and a head swing mechanism 48 that rotates the head 4 around an axis orthogonal thereto. As shown in FIG. 3, two CCD cameras 50 are arranged in the head 4 so as to be freely viewed in stereo, and an audio input / output device 52 is arranged.

  With the above configuration, the leg 2 has six joints for the left and right legs and is given a total of 12 degrees of freedom. By driving the six joints at appropriate angles (joint displacement), the leg 2 A desired movement can be given to the robot 1 and the robot 1 can be arbitrarily walked in a three-dimensional space. Also, the arm portion 5 has five joints for the left and right arms and is given a total of 10 degrees of freedom, and can drive the five joints at appropriate angles (joint displacement) to perform a desired work. Can do. Further, the head 4 is provided with a joint or swing mechanism having two degrees of freedom, and the head 4 can be directed in a desired direction by driving these at an appropriate angle.

  Each of the electric motors 10 and the like is provided with a rotary encoder (not shown), and outputs a signal indicating at least one of an angle, an angular velocity, and an angular acceleration of a corresponding joint through rotation of a rotating shaft of the electric motor. Note that the electric motor 10 and the like are specifically DC servo motors.

  A known six-axis force sensor (hereinafter referred to as “force sensor”) 56 is attached to the foot portion 22, and among the external forces acting on the robot, the three-direction component Fx of the floor reaction force acting on the robot 1 from the ground contact surface, A signal indicating the three-direction components Mx, My, Mz of Fy, Fz and moment is output.

  A force sensor (six-axis force sensor) 58 of the same kind is attached between the wrist joint and the hand 40, and an external force other than the floor reaction force acting on the robot 1, specifically, an external force acting on the hand 40 from the object. Signals indicating the three-direction components Fx, Fy, Fz of (object reaction force) and the three-direction components Mx, My, Mz of moment are output.

  A tilt sensor 60 is installed on the base 3, and a signal indicating a state quantity such as the tilt (tilt angle) of the base 3 with respect to the vertical axis and its angular velocity, that is, the tilt (posture) of the base 3 of the robot 1, etc. Output.

  The output group of these force sensors 56 and the like is sent to an electronic control unit (Electric Control Unit; hereinafter referred to as “ECU”) 70 composed of a microcomputer housed in the storage unit 6 (on the right side of the robot 1 for convenience of illustration). Only the input and output are illustrated). The ECU 70 includes a microcomputer including a CPU, a memory, an input / output interface, and the like, and controls the driving of the electric motor 10 and the like constituting each joint by calculating a joint angle displacement command so that the robot 1 can move in a stable posture. To do.

  As described above, the base 3 stores the battery (voltage source) 7, and the storage 6 stores a DC / DC converter (not shown) that transforms the output voltage (DC voltage) of the battery 7 and an electric motor. A power supply box 74 including a drive circuit (motor driver) 72 such as 10 is stored, and a wireless system 76 is also stored.

  Similarly, the ECU 70 is connected to an operation ECU 78 including a microcomputer via a wireless system 76 so as to be communicable. The operation ECU 78 includes an operation user I / F 78 a, and a command such as an emergency stop input by the user (operator) from the operation user I / F 78 a is sent to the ECU 70 through the wireless system 76.

  FIG. 4 is a block diagram showing the configuration of the ECU 70 with a focus on the electrical system.

  As illustrated, the ECU 70 includes a CPU 70a and an I / O 70b. In addition, one drive circuit 72 per two motors is connected to the drive circuit 1 and the drive circuit 2 in the electric motor 10 and the like (partially shown on the right side of the leg 2 etc. The same applies to the part 4 and the arm part 5).

  The drive circuit 72 is disposed in a power supply circuit 7a that connects the battery (voltage source) 7 and the electric motor (only shown for the electric motor 10R). The force sensor 56 is connected to the A / D conversion circuit 56a. Each of the drive circuit 72, the A / D conversion circuit 56a, and the like are connected to the CPU 70a via the I / O 70b. An overcurrent prevention circuit 80 is inserted in the power supply circuit 7a, which will be described later.

  FIG. 5 is a block diagram functionally showing the operation of the CPU 70a shown in FIG. 4 including that as an overcurrent prevention device.

  As illustrated, the CPU 70a includes a leg control unit 70a1, an arm control unit 70a2, and a head control unit 70a3. The leg control unit 70a1 calculates the gait according to the sensor output sent from the force sensor 56 and the inclination sensor 60 via the I / O 70b based on the gait parameters generated in advance and stored in the memory (not shown). Based on the generated gait, a joint angle command value (energization command value) is determined, and the drive circuit 72 is arranged to eliminate the deviation from the joint angle detected from the output (not shown) of the rotary encoder. The electric motor 10 and the like are driven via Thus, each drive circuit 72 is driven by energizing the corresponding electric motor in accordance with the energization command.

  The arm control unit 70a2 and the head control unit 70a3 also calculate a joint angle command value based on the generated gait and the output of the force sensor 56 and the like, and drive the corresponding electric motor 30 and the like via the drive circuit 72. To do. Further, the arm control unit 70a2 controls the drive of the arm unit 5 according to the work content, and the head control unit 70a3 controls the drive of the electric motor 46 or the head swing mechanism 48 according to an instruction of the image recognition system.

  In the illustrated configuration, the overcurrent prevention circuit 80 described above is inserted in the power supply circuit 7a.

  FIG. 6 is a block diagram specifically showing the configuration of the overcurrent prevention circuit 80.

  As shown in the figure, the overcurrent prevention circuit 80 is inserted into the power supply circuit 7a and cuts off the power supply circuit 7a when it is turned off. The current sensor 80b that produces an output corresponding to the current passed through 10 or the like is compared with the output of the current sensor 80b (indicated by the value V1) with a threshold value (indicated by the value Va). When the output exceeds the threshold value, an overcurrent suppressing unit is provided that performs a switching operation of operating the switching element 80a for intermittently shutting off the power supply circuit 7a for a first predetermined time.

  Specifically, the overcurrent suppression means is a comparator (comparator) in which the output of the current sensor 80b is input to the + input terminal and a predetermined voltage is input to the − input terminal as a threshold value (indicated by the value Va). 80c, the first delay circuit 80d that receives the output of the comparator 80c (indicated by the value V2) and delays it for a predetermined time T1 (for example, 10 to 20 msec), and the output of the first delay circuit 80d (indicated by the value V3) ) And a second delay circuit 80e that is delayed by a predetermined time T2 (first predetermined time, for example, 100 to 200 msec), an output of the first delay circuit, and an output (value V4) of the second delay circuit An EX-OR (exclusive OR) circuit 80f, and an AND circuit 80g, whose outputs are input in parallel. The output of the AND circuit 80g is output via the inverter 80g1 to form a NAND circuit. The outputs of the EX-OR circuit 80f and the AND circuit 80g are indicated by values V5 and V6.

  FIG. 7A is a block diagram showing details of the first delay circuit 80d, and FIG. 7B is a graph showing its characteristics. In FIG. 6A, when the resistance R1 is set to a value much larger than R2, the fall of V3 is steeper than the rise as shown in FIG. Although not shown in the drawing, the second delay circuit 80e also has a point that the value of a resistor or the like is changed so that the delay time T2 is extended to about 10 times that of the first delay circuit 80d. Its composition is not different.

  Returning to the description of FIG. 6, the overcurrent suppressing means is further connected to an oscillator 80h, a buffer 80i connected to the oscillator 80h to which the pulse output is input, an AND circuit (NAND circuit) 80g, and the ECU 70. An AND circuit 80j for inputting these outputs and an insulated gate driver 80k connected to the AND circuit 80j via a resistor and connected to the buffer 80i. The insulated gate driver 80k is connected to the FET 80a through a resistor. The output V6 of the AND circuit 80g is latched by the latch circuit 80l and released by the ECU 70.

  The buffer 80i is connected to the EX-OR circuit 80f. When the output of the EX-OR circuit 80f is at the H level, the pulse output of the oscillator 80h is output as it is, and when the output of the EX-OR circuit 80f is at the L level, the output is high. It becomes an impedance state (no output is generated).

  8 and 9 are time charts showing the operation of the overcurrent prevention circuit 80 shown in FIG. FIG. 8 shows a case where the overcurrent state (overload state) continues for T1 + T2 or more, and FIG.

  The operation of the overcurrent prevention circuit 80 shown in FIG. 6 will be described with reference to FIG. 8. If the output of the current sensor 80b exceeds the threshold value Va at time t1, the output V2 of the comparator 80c becomes H level. However, the output V3 is delayed by T1 by the first delay circuit 80d. This is to eliminate malfunction due to noise or the like.

  When the output V3 of the first delay circuit 80d becomes H level at time t2, the input of the EX-OR circuit 80f also becomes H level. On the other hand, the output V3 of the first delay circuit 80d is delayed by T2 by the second delay circuit 80e, so that the output V4 remains at the L level. The reason why the second delay circuit 80e is provided and delayed by T2 is to confirm whether or not the overcurrent is transient. From that intention, T2 is set to a value about 10 times T1.

  Therefore, at time t2, the output V5 of the EX-OR circuit 80f becomes H level. On the other hand, the input V4 to the AND circuit 80g is at the L level, but as a result of the output being inverted by the inverter 80g1, the output V6 of the AND circuit 80g is also at the H level.

  The output V6 of the AND circuit 80g passes through the latch circuit and is sent to the AND circuit 80j. The output of the ECU 70 is input to the other of the AND circuit 80j. Since the ECU 70 normally outputs an ON signal (H level signal), the output of the AND circuit 80j is at the H level.

  As a result, the pulse output of the oscillator 80h is supplied to the gate terminal of the FET 80a via the insulated gate driver 80k. The FET 80a becomes conductive at the H level (gate potential) of the pulse output and energizes the drive circuit 72, and becomes non-conductive at the L level and stops energization. As described above, the FET 80a is turned on / off to perform the switching operation, whereby the power supply to the power supply circuit 7a in which the drive circuit 72 is disposed is intermittently interrupted, and the power supply amount, in other words, the overcurrent is suppressed. Is done.

  Next, as long as the overcurrent continues to be detected, the output V4 of the second delay circuit 80e becomes H level at time t3, so that the output of the EX-OR circuit 80f becomes L level and the output of the AND circuit 80g also L level. Therefore, the output of the AND circuit 80j is also at the L level. As a result, the output of the insulated gate driver 80k becomes L level, the FET 80a is turned off (non-conducting), and all the energization to each drive circuit 72 is cut off. Since the buffer 80i is in a high impedance state when V5 is at L level, no output is generated.

  As shown in FIG. 8, when no overcurrent is detected at time t4, the output V2 is inverted to the L level. As shown in FIG. 7B, when the current decreases (returns to a normal value), the output V3 and V4 are also almost simultaneously inverted to the L level because the delay is hardly delayed.

  The FET 80a remains off until the ECU 70 releases the latch in the OFF state.

  When the latch is released by the ECU 70, the output of the insulated gate driver 80k becomes the H level, the FET 80a is turned on (becomes conductive), and the energization to the drive circuit 72 is resumed. Since the buffer 80i is in a high impedance state when V5 is at L level, no output is generated.

  In the case shown in FIG. 9, since the output of the current sensor 80b becomes less than the threshold value Va at time t3 and no overcurrent is detected, the values V2, V3, V4 and V5 are all at the L level. As a result, after the switching operation is performed, energization to the drive circuit 72 is resumed without being interrupted.

  FIG. 10A is an explanatory graph showing a transition of current and voltage by the operation of this embodiment, and FIG. 10B is an explanatory graph showing a case where overcurrent protection is simply performed when an overcurrent flows. is there. As shown in FIG. 4B, a large current flows without an overcurrent protection function. However, when the overcurrent protection function is present, the current suddenly decreases, so that the robot 1 stops functioning or the posture becomes unstable. Invite.

  On the other hand, in the case of this embodiment shown in FIG. 6A, the switching operation is performed only during the overcurrent flow, so that the voltage drop is slight. That is, by limiting the current suppression while an overcurrent is detected, it is possible to minimize a decrease in the amount of energization below the threshold value Va.

  Therefore, although the motion algorithm of the robot 1 does not become as intended, when the foot 22 of the robot 1 trips over a protrusion on the road surface and an overcurrent flows through the electric motors 18, 20, the event is usually Since it can be avoided in about several hundred msec, it is considered that the posture can be recovered by motion control (by the joint angle command value) after returning to the normal operation.

  That is, in this embodiment, an overcurrent caused by an abnormality in the system such as a short circuit of wiring and an overcurrent caused by an excessive load for a short period due to a foot 22 tripping on a protrusion during walking are represented by a delay time. A distinction is made by providing T2, and the power supply circuit 7a is intermittently cut off only while an overcurrent flows. Thereby, it is possible to prevent the function stop and the posture of the robot 1 from becoming unstable regardless of the situation while protecting the electrical system such as the electric motors 18 and 20. In particular, in this embodiment, since the robot 1 is a legged mobile robot, it is beneficial to avoid an unstable posture.

  Furthermore, since the overcurrent prevention circuit 80 is configured from a discrete circuit, the configuration is simplified.

  Further, in the overcurrent prevention circuit 80, when the output V1 of the current sensor 80b exceeds the threshold value Va, after T1 (second predetermined time) elapses, during T2 (first predetermined time). Since the switching operation is performed, the overcurrent can be reliably detected while eliminating the influence of noise and the like in addition to the above-described effects.

  FIG. 11 is a block diagram similar to FIG. 5, showing an overcurrent prevention device according to a second embodiment of the present invention.

  The description will focus on the differences from the first embodiment. In the second embodiment, the temperature sensor 90 is provided to detect the outside air temperature TA, and the threshold value Va and the predetermined time T2 (in accordance with the detected value) The ECU 70 (more precisely, the CPU 70a) includes an overcurrent prevention unit 70a4 that performs an overcurrent prevention operation using a software technique.

  Specifically, as indicated by an imaginary line in FIG. 2, the temperature sensor 90 is arranged at an appropriate position facing the outside in the storage unit 6 in the second embodiment, and outputs a signal indicating the outside air temperature TA around the robot 1. To do. In addition, the same code | symbol is attached | subjected to the member same as 1st Example, and description is abbreviate | omitted.

  FIG. 12 is a flowchart showing the overcurrent prevention operation of the CPU 70a.

  Explained below, the outside air temperature TA detected through the temperature sensor 90 in S10 is read out, and the process proceeds to S12 to search the characteristic shown in FIG. 13A from the read out outside air temperature TA and search for the threshold value Va. And the characteristic shown in FIG. 13B is searched to select a predetermined time T2 (first predetermined time).

  The threshold value Va is set so as to decrease as the outside air temperature TA increases. This is because when the outside air temperature TA is high, it is predicted that the electric motors 18 and 20 and their drive circuits 72 will rise in temperature, so that an overcurrent is easily detected. The predetermined time T2 is also set so as to decrease as the outside air temperature TA increases. This is also for the same reason to shorten the switching operation time and accelerate the energization to the drive circuit 72.

  Next, in S14, it is determined whether or not the detected output V1 of the current sensor 80b exceeds the threshold value Va, more precisely, the value selected in S12. When the result in S16 is negative, the subsequent processing is skipped. When the result is positive, the process proceeds to S16, the value of the timer counter TC1 is incremented by one, and the process proceeds to S18, where the value of the timer counter TC1 exceeds T1 described above. Judge whether or not. When the result in S18 is negative, the program returns to S16.

  On the other hand, when the result in S18 is affirmative, the process proceeds to S20, and the switching operation of the FET 80a described in the first embodiment is started.

  Next, in S22, the value of the second timer counter TC2 is incremented by one, and in S24, it is determined whether or not the value of the timer counter TC2 exceeds the selected T2. When the result in S24 is negative, the program returns to S20. Thereby, the power supply circuit 7a is intermittently interrupted during T2.

  When the result in S24 is affirmative, the program proceeds to S26, in which it is determined again whether or not the detected output V1 of the current sensor 80b exceeds the threshold value Va. When the result in S26 is negative, the subsequent processing is skipped. When the result is affirmative, the process proceeds to S28, the FET 80a is turned off to shut off the power circuit 7a, and an abnormality alarm is issued via the wireless system 76 and the operation ECU 78. Output. As a result, the power supply circuit 7a is shut off while an overcurrent is detected.

  Since the robot overcurrent prevention device according to the second embodiment is configured as described above, the same effects as those of the first embodiment can be obtained.

  Further, since the outside temperature TA is detected and the threshold value Va and the predetermined time T2 are changed according to the detected outside temperature TA, in addition to the above-described effects, the electric motors 18, 20 and the like tend to rise in temperature. In this case, the overcurrent can be detected early by lowering the threshold value, and the energization of the drive circuit 72 can be cut off early by shortening the predetermined time T2, thereby further reducing the drive circuit 72 and the like. It can be well protected.

  Further, when the power supply circuit 7a is shut off by turning off the FET 80a, an abnormality alarm signal is output, so that in addition to the above effects, the user (operator) recognizes that an abnormality in which an overcurrent flows has occurred. be able to.

  In the above description, when there is a margin in the resistance of the FET 80a to the temperature, the predetermined time T1 may be extended according to the detected outside air temperature TA. Thereby, the influence by noise etc. can be eliminated further.

  Further, a temperature sensor may be added to detect the temperature of the battery 7 or the drive circuit 72, and the threshold value Va and / or T2 may be changed accordingly. Further, a voltage sensor may be provided to similarly detect the voltage of the battery 7 or the drive circuit 72 and change the threshold value Va and / or T2 accordingly. Furthermore, the threshold value Va and / or T2 may be changed in consideration of the walking conditions of the robot.

  FIG. 14 is a block diagram similar to FIG. 6, showing an overcurrent prevention device according to a third embodiment of the present invention.

  Description will be made focusing on differences from the first and second embodiments. In the third embodiment, a configuration similar to the second embodiment is realized by the configuration of the first embodiment. That is, apart from the ECU 70, a second ECU (ECU2) 92 composed of a one-chip microcomputer is provided in the vicinity of the temperature sensor 90 and connected by an appropriate cable (not shown) or the like, and the second ECU 92 is connected to the temperature sensor 90. The output TA is input, and the second ECU 92 changes the value corresponding to the threshold value Va input to the negative input terminal of the comparator 80c based on the input value.

  More specifically, the second ECU 92 inputs the output TA of the temperature sensor 90 after A / D conversion, determines an appropriate voltage value Va according to the characteristics shown in FIG. (Voltage value Va) is input to the negative input terminal of the comparator 80c. The connection path connecting the second ECU 92 to the comparator 80 c is branched and connected to the battery 7 via a pull-up resistor 94. The remaining configuration is not different from the first embodiment.

  In the third embodiment, by configuring as described above, the same effects as in the second embodiment can be obtained except that T2 cannot be changed according to the detected outside air temperature TA. Further, the output of the temperature sensor 90 is an analog output that is relatively susceptible to noise. However, since the second ECU 92 is provided separately from the ECU 70, the second ECU 92 is installed in the vicinity of the temperature sensor 90 and the connection cable is connected. The length can be shortened and malfunctions can be avoided.

  As described above, in the first to third embodiments, a plurality of links (for example, the thigh link 24 and the crus link 26) connected through the joint and an electric motor (for example, an electric motor) disposed in the joint. A motor 16), a voltage source (battery) 7, and a drive circuit 72 that is disposed in a power supply circuit 7a that connects the electric motor and the voltage source and energizes and drives the electric motor in accordance with an energization command. In the robot 1, an FET (switching element) 80 a that is inserted in the power supply circuit and shuts off the power supply circuit when turned off, and an output corresponding to a current supplied to the electric motor through the drive circuit And the current sensor output V1 is compared with a threshold value Va. When the current sensor output exceeds the threshold value, a first predetermined time ( 2) Overcurrent suppressing means (comparator 80c, first delay circuit 80d, second delay circuit 80e, EX−) that intermittently cuts off the power supply circuit by executing a switching operation for turning on / off the switching element. An OR circuit 80f, an AND circuit 80g, an oscillator 80h, a buffer 80i, an AND circuit 80j, an insulated gate driver 80k, a latch circuit 80l, an ECU (CPU 70a), overcurrent prevention units 70a4 and S10 to S28) are provided.

  In addition, the overcurrent suppressing means performs the switching operation for the first predetermined time (T2) after the second predetermined time (T1) has elapsed when the output of the current sensor exceeds the threshold value. It is configured to execute (S10 to S22).

  Also, the base 3, the plurality of legs 2 connected to the base via a first joint, and the legs connected to the respective tips of the plurality of legs via a second joint 22, a plurality of electric motors 10 and the like respectively disposed at the first and second joints, a voltage source (battery) 7, and a power supply circuit 7a connecting the plurality of electric motors and the voltage source. In a robot, and more specifically, in the legged mobile robot 1, including at least a drive circuit 72 that energizes and drives each of the plurality of electric motors in response to an energization command, the power circuit 7a When inserted and turned off, an FET (switching element) 80a that shuts off the power supply circuit, a current sensor 80b that generates an output corresponding to a current supplied to the plurality of electric motors through the drive circuit, Current The output V1 of the sensor is compared with a threshold value Va, and when the output of the current sensor exceeds the threshold value for a first predetermined period (T2), the switching element is turned off to shut off the power supply circuit. Overcurrent suppression means (comparator 80c, first delay circuit 80d, second delay circuit 80e, EX-OR circuit 80f, AND circuit 80g, oscillator 80h, buffer 80i, AND circuit 80j, insulated gate driver 80k, latch circuit 80l , ECU (CPU 70a), overcurrent prevention unit 70a4, S10 to S28).

  Further, a temperature sensor 90 for detecting the outside air temperature TA is provided, and the overcurrent suppressing means is configured to change the threshold value Va based on the detected outside air temperature TA (S12, second ECU 92). did.

  Further, the temperature sensor 90 for detecting the outside air temperature TA is provided, and the overcurrent suppressing means is configured to change the first predetermined time (T2) based on the detected outside air temperature TA (S12). .

  The overcurrent suppression means is configured to output an abnormal alarm signal when the switching element is turned off to shut off the power supply circuit (S28).

  Further, the robot 1 is configured as a legged mobile robot.

  In the above description, only one current sensor 80 b is provided, but it may be provided for each drive circuit 72.

  Moreover, although the biped robot was illustrated as a legged mobile robot, it is not restricted to it, A robot with 3 or more legs may be sufficient.

1 is a front view of a robot, specifically a legged mobile robot, targeted by an overcurrent prevention device for a mobile robot according to a first embodiment of the present invention. FIG. It is a side view of the robot shown in FIG. It is explanatory drawing which shows the robot shown in FIG. 1 with a skeleton. It is a block diagram which shows the structure of the control unit shown in FIG. 3 centering on an electrical equipment system. FIG. 5 is a block diagram functionally showing the operation of the CPU shown in FIG. 4 including that as an overcurrent prevention device. FIG. 6 is a block diagram specifically showing the configuration of the overcurrent prevention circuit shown in FIG. 5. (A) is a block diagram showing details of the first delay circuit, (b) is a graph showing its characteristics. 7 is a time chart showing an operation of the overcurrent prevention circuit shown in FIG. 6. Similarly, it is a time chart which shows operation | movement of the overcurrent prevention circuit shown in FIG. (A) is explanatory graph which shows transition of the electric current and voltage by operation | movement of the overcurrent prevention circuit shown in FIG. 6, (b) is explanatory graph which shows the case where only overcurrent protection is performed when overcurrent flows. . FIG. 6 is a block diagram similar to FIG. 5 illustrating an overcurrent prevention device according to a second embodiment of the present invention. 12 is a flowchart showing the operation of the apparatus shown in FIG. It is a graph which shows the table characteristic of threshold value Va and T2 (1st predetermined time) with respect to outside temperature TA used by the process of FIG. It is a block diagram similar to FIG. 6 which shows the overcurrent prevention apparatus which concerns on 3rd Example of this invention.

Explanation of symbols

1 Legged mobile robot (robot)
2 Leg 3 Base 7 Battery (Voltage source)
7a Power circuit 10, etc. Electric motor 22 Foot 24 Thigh link (link)
26 Lower leg link
70 Electronic Control Unit (ECU)
70a CPU (overcurrent suppression means)
70a4 Overcurrent prevention part (overcurrent suppressing means)
72 Drive circuit 80 Overcurrent prevention circuit 80a Switching element (FET)
80b current sensor 80c comparator (overcurrent suppression means)
80d first delay circuit (overcurrent suppressing means)
80e Second delay circuit (overcurrent suppressing means)
80f EX-OR circuit (overcurrent suppression means)
80g AND circuit (overcurrent suppression means)
80h Oscillator (overcurrent suppression means)
80i buffer (overcurrent suppression means)
80j AND circuit (overcurrent suppression means)
80k insulated gate driver (overcurrent suppression means)
90 Temperature sensor 92 Second ECU (ECU2)

Claims (7)

  A plurality of links coupled via a joint, an electric motor disposed at the joint, a voltage source, and a power supply circuit connecting the electric motor and the voltage source, and the electric motor according to an energization command In a robot comprising at least a drive circuit that is energized and driven, a switching element that is inserted into the power supply circuit and shuts off the power supply circuit when turned off, and energizes the electric motor via the drive circuit A current sensor that produces an output in accordance with the current to be applied, and the output of the current sensor is compared with a threshold value. When the output of the current sensor exceeds the threshold value, the switching element is turned on for a first predetermined time. An overcurrent prevention apparatus for a robot, comprising: an overcurrent suppressing unit that intermittently cuts off the power supply circuit by executing a switching operation for turning on / off.   The overcurrent suppressing means, when the output of the current sensor exceeds the threshold value, executes the switching operation for the first predetermined time after a second predetermined time has elapsed. Item 2. The robot overcurrent prevention device according to Item 1.   A base, a plurality of legs connected to the base via a first joint, a foot connected to the respective tips of the plurality of legs via a second joint, and the first A plurality of electric motors arranged at the first and second joints, a voltage source, and a power supply circuit connecting the plurality of electric motors and the voltage source, and the plurality of electric motors according to an energization command; In a robot comprising at least a drive circuit for energizing and driving each of the motors, a switching element that is inserted in the power supply circuit and shuts off the power supply circuit when turned off, and the plurality of the drive circuits via the drive circuit. A current sensor that generates an output in accordance with a current that is passed through each of the electric motors, and the output of the current sensor is compared with a threshold value. When exceeding Overcurrent prevention apparatus for a robot, characterized in that a overcurrent suppressing means for the switching element turns off to cut off the power supply circuit.   4. The temperature sensor according to claim 1, further comprising a temperature sensor for detecting an outside air temperature, wherein the overcurrent suppressing means changes the threshold value based on the detected outside air temperature. The overcurrent prevention device for the robot described.   4. The temperature sensor according to claim 1, further comprising a temperature sensor for detecting an outside air temperature, wherein the overcurrent suppressing means changes the first predetermined time based on the detected outside air temperature. An overcurrent prevention device for a robot according to claim 1.   The robot overcurrent prevention device according to any one of claims 3 to 5, wherein the overcurrent suppressing unit outputs an abnormality alarm signal when the switching element is turned off to shut off the power supply circuit. .   The robot overcurrent prevention device according to claim 1, wherein the robot is a legged mobile robot.

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